MIL-STD-209 Lifting And Tiedown ProvisionsThis standard establishes dimensional limits, design considerations, positioning requirements, and strength requirements for lifting to include helicopter sling load HSL and tiedown provisions for lifting or tying down tanks and other tracked vehicles, tactical wheeled vehicles, helicopters, and other military equipment shipped assembled or disassembled in unboxed or uncrated condition, and for restraining cargo or accessories to such equipment. The lifting and tiedown requirements in this standard are necessary to permit compatibility between military equipment and the transportation systems used for deployments.

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MIL-STD-209K

5.6.4  Provision Dimensions.

The minimum diameter of the opening size shall be as follows:

10,000 pound provisions  - 1-5/8 inches

20,000 pound provisions  -  2 inches

25,000 pound provisions  -  2-1/2 inches

50,000 pound provisions  -  3 inches

5.6.5  Qualification.

The supplemental air transport tiedown provisions shall be qualifed through analysis or testing as follows:

a.  A static independent pull to the required design limit load shall be conducted on selected supplemental air transport tiedown provisions.  Selection will be based on difference in provision design and mounting location.

b.  Loads applied to each provision shall be measured with an appropriate measuring device, such as a load cell or dynamometer.

c.  The points used to apply the load to the equipment shall be located so they do not interfere with or reduce the loading on the structural member next to the supplemental air transport tiedown provisions.

d.  The load shall be applied from the provisions in the resultant directions as permitted by the range of restraint capabilities (see Figure 13).  As a minimum, at least one pull 30° downward from the horizontal axis (in the vertical direction) and 30° outward from this same axis (in the lateral direction) is required (see Figure 14). As determined by the physical geometry of the provision, one additional pull 90° vertically downward and one pull 90° directly outward may be required.  If the provisions can

provide restraint in both the fore and aft directions and cannot be qualified by symmetry, the load described above shall be applied in both directions.  The loads shall be applied for not less than 6.0 seconds and shall be not less than the required design limit load as defined in paragraph 5.6.3.

e.  Failure is defined as any visible permanent deformation, yielding, or bending to the provision or other structural component.  A possible failure indication during the initial material analysis shall be justification to use more detailed analysis and testing methods (for example, calibrated measurements, finite element analysis, magnetic particle inspection, X-ray, fatigue testing, ultimate testing, and so forth).  Cracks in welds will constitute test failure.

f.  The contractor shall provide a material analysis showing the ultimate load is not less than 1.5 times the required design limit load for the provisions.

Source:  https://assist.dla.mil  --  D2o3wnloaded:  2014-09-28T23:10Z Check  the  source  to  verify  that  this  is  the  current  version  before  use.